PyQt5如何将QListWidget选中项更新到当前焦点对应的QLineEdit控件

问题根源 #

每次切换输入框焦点时，你都重新给QListWidget的clicked信号绑定了新的槽函数，但旧的信号连接没有被主动移除。点击列表项时，所有历史绑定的槽函数都会依次执行，最终会将内容写入最早绑定的输入框，所以看起来只有第一个文本框会被更新。

修复方案 #

方案1：最小改动（保留原有代码结构） #

只需要在绑定新信号前，先断开QListWidget之前的clicked信号连接即可，修改主文件的on_focusChanged方法：

def on_focusChanged(self):
    fwidget = QtWidgets.QApplication.focusWidget()
    if fwidget is not None:
        focus_widget_name = fwidget.objectName()
        # 新增：断开之前所有绑定的clicked信号连接
        try:
            self.lb1.clicked.disconnect()
        except TypeError:
            # 没有已绑定的信号时跳过异常
            pass

        if focus_widget_name == "tb1":
            self.lb1.clear()
            self.lb1.addItems(data_1)
            self.getdetails_1 = My_File(self.tb1, self.lb1)

        if focus_widget_name == "tb2":
            self.lb1.clear()
            self.lb1.addItems(data_2)
            self.getdetails_1 = My_File(self.tb2, self.lb1)

        if focus_widget_name == "tb3":
            self.lb1.clear()
            self.lb1.addItems(data_3)
            self.getdetails_1 = My_File(self.tb3, self.lb1)

方案2：更简洁的优化写法 #

不用反复创建My_File实例，将逻辑整合到主类中，性能更高：

import sys

from PyQt5 import QtWidgets

data_1 = ["America","India","Russia","Brazil","Swden","China"]
data_2 = ["Apple","Mango","Grapes","Pine","Berry","Banana"]
data_3 = ["item001","item002","item003","item,004","item005","item006"]

class Example(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Example")
        self.tb1 = QtWidgets.QLineEdit()
        self.tb1.setObjectName("tb1")
        self.tb2 = QtWidgets.QLineEdit()
        self.tb2.setObjectName("tb2")
        self.tb3 = QtWidgets.QLineEdit()
        self.tb3.setObjectName("tb3")
        self.lb1 = QtWidgets.QListWidget()
        # 存储当前要写入的目标文本框
        self.current_target = None

        self.vbox = QtWidgets.QVBoxLayout()
        self.hbox = QtWidgets.QHBoxLayout()
        self.vbox.addWidget(self.tb1)
        self.vbox.addWidget(self.tb2)
        self.vbox.addWidget(self.tb3)
        self.hbox.addLayout(self.vbox)
        self.hbox.addWidget(self.lb1)
        self.setLayout(self.hbox)

        # 只绑定一次列表点击事件
        self.lb1.clicked.connect(self.fill_textbox)
        QtWidgets.QApplication.instance().focusChanged.connect(self.on_focusChanged)

    def fill_textbox(self):
        selected_item = self.lb1.currentItem()
        if self.current_target and selected_item:
            self.current_target.setText(selected_item.text())
            self.current_target.setFocus()

    def on_focusChanged(self):
        fwidget = QtWidgets.QApplication.focusWidget()
        if fwidget in [self.tb1, self.tb2, self.tb3]:
            self.current_target = fwidget
            self.lb1.clear()
            if fwidget.objectName() == "tb1":
                self.lb1.addItems(data_1)
            elif fwidget.objectName() == "tb2":
                self.lb1.addItems(data_2)
            elif fwidget.objectName() == "tb3":
                self.lb1.addItems(data_3)

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    win = Example()
    win.show()
    sys.exit(app.exec_())

两种方案都可以实现需求：哪个输入框获得焦点，点击列表项就会把选中内容写入对应输入框。

内容的提问来源于stack exchange，提问作者tckraomuqnt